Which treaty established Portugal's claim to Brazil and Spain's claim to the rest of the Americas?

The Treaty of Tordesillas, signed in 1494, was a pivotal agreement between Portugal and Spain, aimed at resolving conflicts over newly discovered lands in the Americas and other territories. Under this treaty, the Pope divided the newly discovered lands outside Europe between the two nations along a meridian. This allowed Portugal to claim territory in Brazil, while Spain was granted rights to most of the remaining lands in the Americas.

The treaty was significant because it provided a framework for the age of exploration and colonization by establishing clear territorial claims. This meant that Portugal was able to solidify its rights over Brazil, which became a vital part of its empire due to its resources and strategic location, while Spain's claims extended to vast portions of the continent, which would lead to significant territorial expansion and colonization.

Other treaties mentioned in the options, like the Treaty of Paris, the Treaty of Utrecht, and the Treaty of Fontainebleau, pertain to different historical conflicts and issues, such as territory redistribution after wars in the 18th and 19th centuries, rather than the initial claims to lands in the Americas established by the Treaty of Tordesillas.